<template>
  <view>
    <!-- 使用自定义的搜索组件 -->
    <my-search @click="goToSearch"></my-search>
    
    <view class="scroll-view-container">
      <!-- 左侧滚动视图效果 -->
      <scroll-view class="left-scroll-view" scroll-y="true" :style="{height: wh + 'px'}">
        <block v-for="(item, i) in cateList" :key="i">
          <view :class="['left-scroll-view-item', i === active ? 'active' : '']" @click="activeChanged(i)">{{item.cat_name}}</view>
        </block>
        
      </scroll-view>
      <!-- 右侧滚动试图区域 -->
      <scroll-view class="right-scroll-view" scroll-y="true" :style="{height: wh + 'px'}" :scroll-top="scrollTop">
        <view class="cate-lv2" v-for="(item2, i2) in cateLevel2" :key="i2">
          <!-- 二级分类标题 -->
          <view class="cate-lv2-title">/ {{item2.cat_name}} /</view>
          <!-- 三级分类列表 -->
          <view class="cate-lv3-list">
            <view class="cate-lv3-item" v-for="(item3, i3) in item2.children" :key="i3" @click="gotGoodsList(item3)">
              <image :src="item3.cat_icon" ></image>
              <text>{{ item3.cat_name }}</text>
            </view>
          </view>
        </view>
      </scroll-view>
    </view>
  </view>
</template>

<script>
  import badgeMix from '@/mixins/tabbar-badge.js'
  export default {
    mixins: [badgeMix],
    data() {
      return {
        // 屏幕当前可用的高度
        wh: 0,
        cateList: [],
        active : 0,
        // 定义二级分类列表
        cateLevel2: [],
        // 滚动条距离顶部的距离
        scrollTop: 0
      };
    },
    onLoad() {
      // 获取当前系统的信息  
      const sysInfo = uni.getSystemInfoSync()
      this.wh = sysInfo.windowHeight - 50
      this.getCateList()
    },
    methods: {
      async getCateList(){
        const {data: res} = await uni.$http.get('/api/public/v1/categories')
        if(res.meta.status !== 200) return uni.$showMag()
        this.cateList = res.message  //所有的一级分类
        // 为二级分类赋值
        this.cateLevel2 = res.message[0].children
      },
      activeChanged(i){
        this.active = i
        // 重新为二级分类赋值
        this.cateLevel2 = this.cateList[i].children
        // 让 scrollTop 的值在 0 与 1 之间切换
        this.scrollTop = this.scrollTop === 0 ? 1 : 0
      },
      // 点击三级分类项跳转到商品页面
      gotGoodsList(item3){
        uni.navigateTo({
            url: '/subpkg/goods_list/goods_list?cid=' + item3.cat_id
        })
      },
      goToSearch(){
        uni.navigateTo({
          url: '/subpkg/search/search'
        })
      }
    }
  }
</script>

<style lang="scss">
.scroll-view-container {
  display: flex;
  
  .left-scroll-view {
    width: 120px;
  } 
  .left-scroll-view-item {
    background-color: #f7f7f7;
    line-height: 60px;
    text-align: center;
    font-size: 12px;
    
    &.active {
      background-color: #ffffff;
      position: relative;
      
      &::before {
        content: ' ';
        position: absolute;
        top: 50%;
        left: 0;
        transform: translateY(-50%);
        display: block;
        width: 3px;
        height: 30px;
        background-color: #c00000;
      }
    }
  }
}
.cate-lv2-title {
  font-size: 12px;
  font-weight: bold;
  text-align: center;
  padding: 15px;
}
.cate-lv3-list {
  display: flex;
  flex-wrap: wrap;
  
  .cate-lv3-item {
    width: 33.33%;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    margin-top: 10px;
    
    image {
      width: 60px;
      height: 60px;
    }
    text {
      font-size: 12px;
    }
  }
}
</style>
